The present invention relates to a cleaning apparatus and an image forming apparatus.
An electrophotographic image formation apparatus includes a transfer unit that transfers toner (developing agent) onto a sheet and a transport unit that transports the sheet to the transfer unit. The transfer unit includes a photosensitive drum on which an electrostatic latent image corresponding to an image to be formed on the sheet is formed, and the transport unit includes a transport roller or a transport belt.
In such an image forming apparatus, the transfer unit supplies toner in correspondence to the electrostatic latent image formed on the photosensitive drum and transfers the toner onto the sheet to form the image on the sheet. In this process, part of the supplied toner attaches to the circulating surfaces of the photosensitive drum and the transport unit and ends up unnecessary toner (waste toner). If printing (image formation) is carried out with the waste toner attached to the circulating surfaces of the photosensitive drum and the transport unit, the waste toner is retransferred onto the sheet or next sheets, so that an unnecessary image that the user does not intend is formed. To address this problem, a cleaning apparatus is typically provided to remove the toner attached to the circulating surfaces of the photosensitive drum and the transport unit.
There is a known cleaning apparatus, such as the one disclosed in JP-A-3-67292 (FIGS. 5 and 6). The cleaning apparatus removes toner from the cylindrical circulating surface of a photosensitive drum that rotates around one pivotal shaft in a housing. The cleaning apparatus includes a stripper blade and a securing section.
The stripper blade has a substantially plate-shape, the width direction of which is parallel to the pivotal shaft and the longitudinal direction of which is perpendicular to the pivotal shaft. One longitudinal end portion of the stripper blade abuts the circulating surface of the photosensitive drum in such a way that the stripper blade is inclined to scoop the toner attached to the circulating surface of the photosensitive drum.
The securing section is secured to the housing at the position downstream of the stripper blade in the circulation direction of the circulating surface of the photosensitive drum, and secures the other longitudinal end portion of the stripper blade through bonding with an adhesive. The securing section integrally includes a counter-bending preventer that extends from the portion where the other end portion of the stripper blade is bonded and secured toward the one end portion of the stripper blade. The counter-bending preventer is not bonded to the stripper blade but disposed along the stripper blade. The one end portion of the stripper blade is thus bent and abuts the circulating surface of the photosensitive drum with the stripper blade inclined thereto.
In the conventional cleaning apparatus having such a configuration, the stripper blade strips and removes waste toner attached to the circulating surface of the photosensitive drum, thus preventing the problem of formation of an unnecessary image that the user does not intend on a sheet.
In the cleaning apparatus, even when the frictional force between the stripper blade and the circulating surface causes deformation of the one end portion of the stripper blade bending toward the downstream side in the circulation direction of the circulating surface (hereinafter referred to as “counter-bending”), the stripper blade abuts the counter-bending preventer and stops there, so that the counter-bending is restricted. The cleaning apparatus can thus prevent the counter-bending of the stripper blade.
Long-term use of such a conventional cleaning apparatus, however, may cause counter-bending of the stripper blade, which may disadvantageously impair the operation of the photosensitive drum, the transport unit and the like. In particular, assuming that the stripper blade has the same positional error, a reduced curvature radius of the circulating surface for a smaller size of the image forming apparatus increases variation of the set angle of the stripper blade with respect to the circulating surface. As a result, it becomes difficult to control the set angle of the stripper blade that abuts the circulating surface within a predetermined range, so that counter-bending of the stripper blade more likely occurs. Accordingly, in the cleaning apparatus, there has been a need to more reliably prevent the counter-bending of the stripper blade.